Efficiency of the entomopathogenic fungus Verticillium lecanii in the ...

More documents

Recommendations

Info

probitprobitprobit2438 Afr. J. Microbiol. Res.Figure 4. Germination of V. lecanii spores after 24 h of incubation at 24°C and at a RH of 100%. G 40X0.75.Table 1. Probit analysis of egg treatment.No. of insects (n) Slope ± SE LC (95%) Chi-square LD50788 0.69±0.10 (13.060-86.134)10 6 12.709 4.2x10 7788 0.73±0.09 (93.573-37.621)10 6 15.929 2.1x10 7788 1.02±0.10 (41.553-79.95)10 6 23.169 0.59x10 764a86b86c20-22 4 6 8 10Log dose of spores/ml420-22 4 6 8 10log dose of spores/ml420-22 4 6 8 10log dose of spores/mlFigure 5. Effect of V. lecanii on T. vaporariorum eggs. Day 5 (a), day 6 (b) and day 7 (c) after treatment.day 5 was 7 folds higher than that found in day 7(Figure 5a, b and c). Microscopic examination showedthat the infected T. vaporariorum egg was surroundedwith V. lecanii mycelium (Figure 6a and b).Effect on larvaeAs seen in Figure 7, the percentage of mortalityincreased according to contact time, whatever wasthe dose of spores used. LD 50 were: 11x10 3 , 3.4x10 3and 0.5x10 3 spores/ml for the three incubation times(Table 2). Figure 8 showed T. vaporariorum larvaewith an abnormal shape surrounded with V. lecaniimycelium.Effect on adultsAfter 7 days of incubation of 120 adult insects, only 81
LD50 (10 3 ) spores/mlBouhous and Larous 2439abFigure 6. A T. vaporariorum egg control (a) A T. vaporariorum egg surrounded with V. lecanii mycelium, (b) G 40X0.75.1510504 5 6 7 8Days after incubationFigure 7. Effect of V. lecanii on T. vaporariorum larvae after 5, 6, and 7 days of treatment.Table 2. Probit analysis of larvae treatment.No. of insects (n) Slope ± SE LC (95%) Chi-square LD50604 0.26± 0.08 17.357 10 3 -94.40 10 5 72.25 11X10 3604 0.30±0.08 42.156 10- 33.495 10 5 61.43 3.4X10 3604 0.28±0.09 25.64 -13.045 10 7 44.32 0.5X10 3were found to be completely invaded by means of thefungus mycelium (Figure 9).Influence of humidityThe incubation at 70% relative humidity did not showany inhibitory effect on the pathogenesis of thefungus, since the mortality rate of the larvae was100% and that of eggs was relatively high (Figure 10).Information about probit analysis (No. of insects(n=885), Slope ± S: 0.88± 0.10, LC (95%): 3.74-7.23,Chi-square: 1.44).DISCUSSIONExperiments on the efficiency of the fungus against T.vaporariorum investigated the influence of variousenvironmental factors. Experimental infections of
Page 3: % of germinationBouhous and Larous
Page 7 and 8: ProbitBouhous and Larous 2441Log ti

Efficiency of the entomopathogenic fungus Verticillium lecanii in the ...

Create successful ePaper yourself

Delete template?

Save as template?